JSP ————> servlet
我的第1个Java Web应用程序——index.jsp
我的第2个Java Web应用程序——welcome-file
我的第3个Java Web应用程序——conf/server.xml
我的第4个Java Web应用程序——jsp page
我的第5个Java Web应用程序——jsp 脚本
我的第6个Java Web应用程序——jsp 声明
我的第7个Java Web应用程序——JSP 表达式
我的第8个Java Web应用程序——JSP页面生命周期
我的第8个Java Web应用程序——我的乘法口诀表！
1
<!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="Generator" content="EditPlus®"> <meta name="Author" content=""> <meta name="Keywords" content=""> <meta name="Description" content=""> <title>Document</title> </head> <body> <h1>???????</h1> </body> </html>
<?xml version="1.0" encoding="ISO-8859-1" ?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
</web-app>
2
<?xml version="1.0" encoding="ISO-8859-1" ?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<welcome-file-list>
<welcome-file>/index.jsp</welcome-file>
</welcome-file-list>
</web-app>
3
4
jsp=java server page
<%@ page language="java" import="java.util.*" contentType="text/html;charset=utf-8" %>
<html>
<body>
<h1 align="center">啤酒推荐</h1>
<p>
<%
List styles = (List)request.getAttribute("styles");
Iterator it = styles.iterator();
while (it.hasNext()) {
out.print("<br>try: " + it.next());
}
%>
</body>
</html>
5
<%@ page language="java" import="java.util.*" contentType="text/html;charset=utf-8" %>
<html>
<body>
<h1 align="center">啤酒推荐</h1>
<p>
<%
List styles = (List)request.getAttribute("styles");
Iterator it = styles.iterator();
while (it.hasNext()) {
out.print("<br>try: " + it.next());
}
%>
<%
out.print("<br /><br />今天天气貌似不错！");
// out是一个内置的对象！
%>
</body>
</html>
6
两种声明方式的差异。参考：http://www.cnblogs.com/zengmiaogen/archive/2012/04/15/2450414.html
我们既可以在<%%>中声明变量，也可以在<%!%>中声明变量，
那么，这两种声明方式有什么区别呢？事实上，<%!%>相当于类的实例域，而<%%>相当于方法体。
// TO-DO
7
<%@ page language="java" import="java.util.*" contentType="text/html;charset=utf-8" %>
<html>
<body>
<p>this is a simple test</p>
<%!
String words = "this is a simple test.";
int sum(int x, int y) {
return x + y;
}
%>
<p>words=<%=words%></p>
<p>3+4=<%=sum(3,4)%></p>
</body>
</html>
8
当我们访问jsp页面的时候，jsp引擎（web容器）首先判断是否是第一次请求...
这个时候我就想，要是可以直接看到它编译出来的字节码就好了，那么到哪里查看呢？——答案是在tomcat的work目录下，不仅有字节码，还有源代码，我们查看一下上一节的代码。
/*
* Generated by the Jasper component of Apache Tomcat
* Version: Apache Tomcat/7.0.77
* Generated at: 2017-06-09 10:07:20 UTC
* Note: The last modified time of this file was set to
* the last modified time of the source file after
* generation to assist with modification tracking.
*/
package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import java.util.*;
public final class test_jsp extends org.apache.jasper.runtime.HttpJspBase
implements org.apache.jasper.runtime.JspSourceDependent {
String words = "this is a simple test.";
int sum(int x, int y) {
return x + y;
}
private static final javax.servlet.jsp.JspFactory _jspxFactory =
javax.servlet.jsp.JspFactory.getDefaultFactory();
private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;
private volatile javax.el.ExpressionFactory _el_expressionfactory;
private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;
public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
return _jspx_dependants;
}
public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
if (_el_expressionfactory == null) {
synchronized (this) {
if (_el_expressionfactory == null) {
_el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
}
}
}
return _el_expressionfactory;
}
public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
if (_jsp_instancemanager == null) {
synchronized (this) {
if (_jsp_instancemanager == null) {
_jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
}
}
}
return _jsp_instancemanager;
}
public void _jspInit() {
}
public void _jspDestroy() {
}
public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
throws java.io.IOException, javax.servlet.ServletException {
final javax.servlet.jsp.PageContext pageContext;
javax.servlet.http.HttpSession session = null;
final javax.servlet.ServletContext application;
final javax.servlet.ServletConfig config;
javax.servlet.jsp.JspWriter out = null;
final java.lang.Object page = this;
javax.servlet.jsp.JspWriter _jspx_out = null;
javax.servlet.jsp.PageContext _jspx_page_context = null;
try {
response.setContentType("text/html;charset=utf-8");
pageContext = _jspxFactory.getPageContext(this, request, response,
null, true, 8192, true);
_jspx_page_context = pageContext;
application = pageContext.getServletContext();
config = pageContext.getServletConfig();
session = pageContext.getSession();
out = pageContext.getOut();
_jspx_out = out;
out.write("\r\n");
out.write("\r\n");
out.write("<html>\r\n");
out.write(" <body>\r\n");
out.write(" \t<p>this is a simple test</p>\r\n");
out.write(" \t");
out.write("\r\n");
out.write(" \t<p>words=");
out.print(words);
out.write("</p>\r\n");
out.write(" \t<p>3+4=");
out.print(sum(3,4));
out.write("</p>\r\n");
out.write(" </body>\r\n");
out.write("</html>");
} catch (java.lang.Throwable t) {
if (!(t instanceof javax.servlet.jsp.SkipPageException)){
out = _jspx_out;
if (out != null && out.getBufferSize() != 0)
try {
if (response.isCommitted()) {
out.flush();
} else {
out.clearBuffer();
}
} catch (java.io.IOException e) {}
if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
else throw new ServletException(t);
}
} finally {
_jspxFactory.releasePageContext(_jspx_page_context);
}
}
}
9
<%@ page language="java" import="java.util.*" contentType="text/html;charset=utf-8" %>
<html>
<body>
<p>这是我的乘法口诀表！</p>
<%
for (int i = 1; i <= 9; ++i) {
for (int j = 1; j <= i; ++j) {
out.print(i + " * " + j + " = " + i*j + " ");
}
out.print("<br />");
}
%>
</body>
</html>
看完视频后修改了一下， 是空格占位符
<%@ page language="java" import="java.util.*" contentType="text/html;charset=utf-8" %>
<html>
<body>
<p>这是我的乘法口诀表！</p>
<%!
void printTable() {
for (int i = 1; i <= 9; ++i) {
for (int j = 1; j <= i; ++j) {
out.print(i + " * " + j + " = " + i*j + " ");
}
out.print("<br />");
}
}
%>
<%
printTable();
%>
</body>
</html>
时间： 2024-12-20 12:24:48